I was admittedly a skeptic of this card at first due to the extremely specific and restrictive mana-cost (just like everybody else here). That said, I have watched enough of him in standard to see that once casting him isn't an issue, he almost acts as a (more?) powerful Consecrated Sphinx, which is very elite company to be in. Once you can cast him he WILL enter play (barring something like Venser, Shaper Savant), and he will at least cantrip (barring a Shriekmaw style creature). If allowed to run wild, he can very easily eclipse the game-impact of other six-drops like Wurmcoil Engine or the Titans. Am I being being a tad hyperbolic? Perhaps. Long story short though, he is not a low-power level card at the very least if you can stomach the very restrictive cost.
(list not current)
My Cube Google Docs Spreadsheet: https://spreadsheets.google.com/spreadsheet/ccc?key=0AibgWfz0ukmOdDNhOHlucjcxUi1wVy00NDhLbDUtUlE&hl=en_US#gid=8
(list is always current)